Fatigue. Every runner knows the feeling — the heaviness in your legs, the urge to slow down or stop, the voice in your head saying, running sucks. But what exactly is fatigue?
In the sporting world, the term is everywhere, yet scientists still don’t have a single definition they all agree on. You can’t place fatigue under a microscope, and each runner experiences it differently.
To explain it, researchers have developed several competing theories, and one of the most intriguing is the Central Governor Model.
When physiologist A.V. Hill first suggested in 1924 that the brain might influence fatigue, the idea was radical. Since then, the Central Governor Theory has sparked debate, scrutiny, and ongoing research into how much control our minds have over our bodies.1NOAKES, T. D. (1998). Maximal oxygen uptake: “classical” versus “contemporary” viewpoints: a rebuttal. Medicine& Science in Sports & Exercise, 30(9), 1381–1398. https://doi.org/10.1097/00005768-199809000-00007
We’ll look at the distinction between peripheral and central fatigue, break down what the Central Governor Model really means, and explore how it affects pacing, mental limits, and even the way you can “hack” your own running performance, along with some of the major scientific challenges to the theory itself.
Peripheral Fatigue Vs Central Fatigue
For decades, fatigue was thought to reside purely in the muscles. Italian physiologist Angelo Mosso helped cement this view in 1891 with his book La Fatica (Fatigue), where he described what became known as peripheral fatigue.2Di Giulio, C., Daniele, F., & Tipton, C. M. (2006). Angelo Mosso and muscular fatigue: 116 years after the first Congress of Physiologists: IUPS commemoration. Advances in Physiology Education, 30(2), 51–57. https://doi.org/10.1152/advan.00041.2005
Peripheral fatigue suggests that the muscle itself is the source of fatigue. Picture a long run: your quads start to burn, your legs feel heavy, and eventually you’re forced to slow down.
According to this model, that sensation comes from local physiological changes within the muscle, such as a buildup of acidity, that impair motor function and reduce performance. In other words, fatigue is caused by local muscle factors.
The Central Governor Model, by contrast, challenges this view. Rather than the muscles themselves shutting down, it proposes that the brain regulates performance, deliberately creating the sensation of fatigue as a protective mechanism.3Kirkendall, D. T. (1990). Mechanisms of peripheral fatigue. Medicine and Science in Sports and Exercise, 22(4), 444–449. https://pubmed.ncbi.nlm.nih.gov/2205780/
The Central Governor Model Explained
The central governor model posits that the brain serves as the body’s control room and safety mechanism. Thus, the brain is ultimately responsible for regulating the body’s ability during exercise.
According to the theory, the brain constantly monitors the body during exercise so that we don’t hurt ourselves. It keeps the body in check, not allowing it to deviate too far from homeostasis (balance).
If the brain senses that the exercise is getting to a level that is potentially dangerous- running too far, too fast, on too little fuel– the brain acts to decrease the intensity level of the exercise.
In the Peripheral Fatigue model, the reason for a runner’s quads to be “burning” is directly a cause of physiological factors, namely a build-up of acidity within the muscle caused by running. However, according to the Central Governor Model, this “burn” is a result of the brain reducing muscle fiber recruitment of the quads.4Noakes, T. D. (2011). Is it Time to Retire the A.V. Hill Model? Sports Medicine, 41(4), 263–277. https://doi.org/10.2165/11583950-000000000-00000
When physiologist A.V. Hill initially proposed the Central Governor Model, he theorised that the heart was not entirely responsible for its own functioning, and that instead, it was protected by some sort of governor, potentially from the nervous system.
Since Hill’s rudimentary theory, the Central Governor Model has been refined. More recently, psychologist Tim Noakes et al. have theorised the Central Governor Model as:
“Exercise performance is regulated by the central nervous system specifically to
Tim Noakes
ensure that catastrophic physiological failure does not occur during normal
exercise in humans.” 5Noakes, T. D. (2005). From catastrophe to complexity: a novel model of integrative central neural regulation of effort and fatigue during exercise in humans: summary and conclusions. British Journal of Sports Medicine, 39(2), 120–124. https://doi.org/10.1136/bjsm.2003.010330
“The subconscious brain sets the exercise intensity by determining the number of motor units that are activated and hence the mass of skeletal muscle that is recruited
Pettersen
throughout the exercise bout.”
An example of the Central Governor Model in action is the long-distance classic: the finish line sprint.
At mile 16 of a marathon, a runner can be all out of gas. They hit the wall. The thought of going a second faster than a walk is out of the question. However, they soldier on, chipping away until the finish line is in sight. And miraculously, 400 meters from the finish line, they hit an all-out sprint.
What has happened here, according to the Central Governor Model, is that the brain has realized that 400 meters from the end, there is no risk involved in picking up the pace, so it opens up biological pathways and allows the body to run faster.
Is It All Mind Over Matter?
It is common for people to hear about the Central Governor Model and to assume that because your brain is in control and not your muscles, that means that you can simply will yourself to run faster or farther by turning off the Central Governor. This is not the case.
Racing is a combination of three important components: emotional, physical, and mental.
You can’t just hijack the central governor. And even if you could turn off the central governor, the physical fitness of an athlete is still a limiting factor.
For example, even without the influence of a central governor, a four-hour marathoner couldn’t suddenly run a two-hour marathon. Their body simply couldn’t meet the extreme energy and physiological demands.
What they can do, however, is learn to stretch the limits of their central governor. Through mental training and visualization techniques, runners can tap into hidden performance reserves and push further than they once thought possible.
Pushing Your Mental Limits With Training
While you can’t completely turn off or overcome the central governor, you can train your mind to improve its ability to tolerate physical discomfort to prepare your mind for the physical demands you place on it while running.
One way in which our Central Governor regulates the body is through the experience of pain. When you’re in pain during a race, you tend to ease off. Great runners can better push through that pain.
Have you heard about the hand in ice water studies?
Studies had athletes and non-athletes submerge their hands in a bucket of ice water for as long as they could. The athletes had a higher pain tolerance and were able to keep their hands submerged for much longer compared to non-athletes.6Pettersen, S. D., Aslaksen, P. M., & Pettersen, S. A. (2020). Pain Processing in Elite and High-Level Athletes Compared to Non-athletes. Frontiers in Psychology, 11(1908). https://doi.org/10.3389/fpsyg.2020.01908
The theory is that the athletes had altered their relationship with pain. They were able to “push through” when the non-athletes could not.
Researchers concluded that the reason the athletes had a higher pain tolerance compared to non-athletes was that their training had impacted the way they withstood pain.
The hours spent training in an uncomfortable or painful physical state had conditioned their brains to tolerate more pain, and this skill transferred to areas outside of sport.
The Central Governor model suggests that the limits of human endurance are flexible. We always have reserves; our brain just withholds them from us.
But with physical training, we can push back at our psychological barriers.
“My unproven hypothesis is that in the case of a close finish, physiology does not determine who wins. Rather somewhere in the final section of the race, the brains of the second, and lower placed finishers, accept their respective finishing positions and no longer challenge for a higher finish.”7Noakes, T. D. (2012). Fatigue is a Brain-Derived Emotion that Regulates the Exercise Behavior to Ensure the Protection of Whole Body Homeostasis. Frontiers in Physiology, 3(82). https://doi.org/10.3389/fphys.2012.00082
– Tim Noakes
The Central Governor Model’s Effect On Pacing
The idea that your brain ultimately controls how far and fast you go has big implications for the way we view pacing.
Pacing is one of the ways in which the brain regulates the body according to the Central Governor Model.
In other words, the brain “anticipates” all the known variables of a race or all-out run– the distance, topography, temperature, etc. – and it then calculates an optimal pace that will get you to cross the finish line without dying or seriously hurting yourself.
More scientifically speaking, according to research by Noakes et al.:
“The brain determines the number of active motor units based on a pacing
Tim Noakes (9)
strategy that will allow completion of a task in the most efficient way while
maintaining internal homeostasis and a metabolic and physiological reserve
capacity.”
When you deviate too far from your optimal physiological pace, your brain responds by reducing the level of muscle activation to slow the body down.
Hack Your Running Using The Central Governor Model
#1: Don’t go off too fast, too early
By speeding off too fast at the beginning of a race, you trigger the central governor early. This means that the brain will trigger physiological changes to slow your body down so that you don’t hurt yourself.
Instead, don’t deviate too much from your original pacing strategy.
#2: Use visualisation techniques
Careful here, you don’t want to be toeing the start line of a marathon or ultra blindly visualising an easy-breezy run.
If you do that, you’ll be setting yourself up for failure. When your Central Governor kicks in (which it will), you’ll be more likely to give in to your brain’s experience of pain and give up, or slip far beneath your goal pace.
Instead, when you’re approaching a race, mentally put yourself in that moment in the race where it gets tough and visualise yourself pushing through it. By visualising yourself overcoming pain and fatigue, you will be better equipped to face the realities of the race.
#3: Incorporate speed sessions into your training
As we saw in the ice water studies above, athletes have a higher pain tolerance due to their time spent in painful conditions in training.
Infamously, the most painful types of running training are speedwork sessions: hill sprints, fartlek workouts, and interval sessions.
By incorporating these kinds of sessions into your training schedule, you’ll be able to chip away at your mental constraints when it comes to pain.
Pro Tip: When you think you’re done and you just can’t do another rep, run a final rep. This is where you’ll bank the biggest reward for your mental toughness come race day.
Challenges To This Model
As mentioned, there is more than one model of fatigue, and not everyone in the sports psychology world is on board with the Central Governor Theory. Here are some challenges to the theory:
#1: There is a lack of evidence
According to Henriette van Praag, PhD, a researcher at the National Institutes of Health, the Central Governor Model “lacks a clear structural/physiological basis within the central nervous system. Thus, empirical evidence for the existence of a ‘governor’ remains to be
established.”
#2: It doesn’t take all factors into account
The Central Governor Model addresses one aspect of fatigue. However, in life, there are many limiting factors of running performance. Motivation and environmental issues, for example.8Weir, J. P. (2006). Is fatigue all in your head? A critical review of the central governor model * Commentary. British Journal of Sports Medicine, 40(7), 573–586. https://doi.org/10.1136/bjsm.2005.023028
Inspirational Quotes From The Sporting Greats
Roger Bannister: “The great barrier is the mental hurdle.”
Derek Clayton: “The difference between my world record and many world-class runners is mental fortitude. I ran, believing in mind over matter.”
Vince Lombardi: “Fatigue makes cowards of us all.”
If you would like to learn more about visualization and how to use it in races, check out this next guide:
Thank you for this interesting read. Personally, I have found visualisation methods to be really beneficial and an integral part of preparation before a race.
On a side note:
“More recently psychologist Tim Noakes et al. have theorised the Central Governor Model as:”
Dr Tim Noakes is primarily trained or qualified as a psychologist, if you have a look at his credentials here ):
QUALIFICATIONS
MBChB: 1974 – University of Cape Town
MD: 1981 – Thesis title – “Exercise and the Heart”
DSc: 2002 – Doctor of Science in Medicine degree in Exercise Science (UCT)
PhD (h.c.): Vrije University, Amsterdam, Netherlands
FACSM: Fellow of the American College of Sports Medicine
(hon) FFSEM (UK): Honorary Fellowship of the Faculty of Sport and Exercise Medicine (UK)
Jacobus, thanks for sharing, and adding to the article.
We’ve got a guide to visualization – I’d be interested in how it matches up with your experiences.
All the best,
Thomas